1  Integer[]        values;

2  values = new Integer[5];

3  for (int i=0; i < values.length; i++)
4  {
5      values[i] = new Integer(i*10);
6  }
  

public class IntNode
{
    public int          value;
    public IntNode      next;
}
  

and the following implementation of a Pew:

public class Pew
{
    private IntNode last;


    public Pew()
    {
	last  = null;
    }

    public void pish(int anInt)
    {
	IntNode temp;

	temp = new IntNode();

	temp.value = anInt;
	temp.next  = last;

	last = temp;
    }
}
  

draw a model of memory that illustrates what happens when the following statements are executed:

  Pew   p;

  p = new Pew();

  p.pish(22);

  p.pish(33);

  p.pish(44);
  

public class Person
{
    public int       age;
    public Person    bestFriend;    
    public String    name;    

    public Person(String name, int age, Person bestFriend)
    {
       this.name       = name;
       this.age        = age;
       this.bestFriend = bestFriend;       
    }   

    public String toString()
    {
       String     s;
       
       s = name + " (" + age + ") ";
       if (bestFriend == null) s += "has no friends";
       else                    s += "is friends with " + bestFriend.name;

       return s;       
    }
    
}
    

what will be printed by the following Driver (assuming everything is compiled and executed properly)? Note: Be careful!

import java.util.*;


public class Driver
{
    public static void main(String[] args)
    {
       Person       alice, bob, carol, dan, temp;
       ArrayList    people;
       

       alice = new Person("Alice", 30, null);
       bob   = new Person("Bob",   32, alice);

       System.out.println(alice.toString());
       System.out.println(bob.toString());
       
       carol = new Person("Carol", 40, null);
       dan   = new Person("Dan",   50, carol);
       carol.bestFriend = dan;

       System.out.println(carol.toString());
       System.out.println(dan.toString());

       people = new ArrayList();
       people.add(alice);
       people.add(bob);
       people.add(carol);
       people.add(dan);
       
       alice.age      = 65;
       bob.bestFriend = carol;
       carol.name     = "Carol Ann";
       dan.age        = 88;
       
       
       for (int i=0; i<people.size(); i++)
       {
          temp = (Person)people.get(i);
          System.out.println(temp.toString());          
       }
       

    }
}
    

• Make all of the attributes private.
• Add a setName(String name).
• Add a setAge(int age) method that throws a NobodyIsThatOldException whenever the age is greater than 39. This exception must be checked. (Note: You will need to write a NobodyIsThatOldException class.)

import java.util.*;

public class Printer
{
    private StringTokenizer         tokenizer;
    

    public void print(String line)
    {
	tokenizer = new StringTokenizer(line, ",");

	if (tokenizer.hasMoreTokens())
	{
	    printTokens(tokenizer);
	}
    }


    private void printTokens(StringTokenizer tokenizer)
    {
	String      token;

	token = tokenizer.nextToken();
	if (tokenizer.hasMoreTokens())
	{
	    printTokens(tokenizer);
	}

	System.out.println(token);
    }

}
  

carefully trace the execution of the following:

public class PrinterDriver
{
    public static void main(String[] args)
    {
	Printer      test;

	test = new Printer();
	test.print("Aboutabl,Bernstein,Harris");
    }
}
  

arithmetic-operator operand1 operand2

For example, the following are valid expressions in prefix notation:

+ 5 3
* 2 8

Suppose we have a Stack class that holds String objects and a method named evaluate in the Calculator class that is passed the three parts of a prefix expression (as String objects) and returns a String representation of the result. Trace the execution of the following, carefully modeling memory at each step:

  Stack      terms;

  terms = new Stack();

  terms.push("5");
  terms.push("3");
  terms.push("+");

  result = Calculator.evaluate(terms.pop(), terms.pop(), terms.pop());

  terms.push(result);
  terms.push("4");
  terms.push("*");

  result = Calculator.evaluate(terms.pop(), terms.pop(), terms.pop());
  

public class Adder
{

   public static void main(String[] args)
   {
      double        result;
      
      try 
      {
         result = add(args);
         System.out.println(args[0]+"+"+args[1]+": "+result);
      }
      catch (ArrayIndexOutOfBoundsException aioobe)
      {
         System.out.println("Too few operands.");
      }
   }




   public static double add(String[] terms) 
                                     throws ArrayIndexOutOfBoundsException
   {
      double        left, result, right;
      String        operator;
      
      left     = 0.0;
      right    = 0.0;
      

      try
      {
         left = Double.parseDouble(terms[0]);
      }
      catch (NumberFormatException nfe)
      {
         left = 0.0;         
      }
      
      try
      {
         right = Double.parseDouble(terms[1]);
      }
      catch (NumberFormatException nfe)
      {
         right = 0.0;         
      }
      
         
      result = right + left;
      
      return result;
   }
}

carefully trace the execution of each the following:

java Adder 5 4
java Adder 5
java Adder 5 b
java Adder 3 4 5 6

import java.util.*;

public class Revenues
{
    private ArrayList<String>     items;

    public Revenues()
    {
        items = new ArrayList<String>();
    }


    /**
     * Add an item value to the collection of revenues
     *
     * @param item   A dollar value (including the leading $ and commas)
     */
    public addItem(String item)
    {
        items.add(item);
    }


    /**
     * Calculates the total of all (valid) items in this collection
     *
     * @return   The total revenue
     */
    public double total()
    {
    







    }
}

• Add a deposit.
• Add a withdrawal.
• Print all withdrawals and deposists (with a running balance).
• Calculate the final/current balance.

It must be possible to call each method more than once. (Hint: Think about how this can be facilitated using the "copy constructor".)

• Add a SavingsAccount.
• Get a SavingsAccount.
• Calculate the total amount of money in all of the SavingsAccount objects.